The present invention relates to a radio communication apparatus that selects and uses a proper one of plural transmission systems, as well as a technique for switching among those transmission systems.
There is a well-known wireless, radio communication system usable for mobile communications, etc. in an environment in which the subject radio channel property is frequently changed. The radio communication system uses a technique for making communications by selecting a proper one of encoding systems, a proper one of modulating systems, etc. respectively. There is also a technique that changes references for selecting those encoding and modulating systems in accordance with the actual communication circumstances. The technique is disclosed in, for example, Japanese Patent Application Laid-Open Publication No. 2003-143654. In this Japanese Patent Application Laid-Open Publication No. 2003-143654, the SIR (Signal to Interference power Ratio) is used to change the MCS (Modulation and Coding Scheme) level and control the received SIR reference value used to change the MCS level in accordance with the actual communication circumstances. The present inventors have disclosed an improved technique of the MIMO (Multiple Input Multiple Output) communication system as a related invention in this technical field of Japanese Patent Application Laid-Open Publication No. 2004-266586.